1. Field of the Invention
The present invention relates to a vehicle driving assist system configured to assist a driver with respect to the operation of a vehicle. More specifically, the present invention relates to a vehicle driving assist system that calculates a risk potential indicative of a degree of convergence between a host vehicle and a preceding obstacle, and that produces a driver notification stimulus based on the risk potential.
2. Background Information
Several conventional vehicle driving assist systems have been proposed for detecting a degree of convergence between a host vehicle and a preceding obstacle based on the distance and relative velocity between the host vehicle and the preceding obstacle. One example of such a system is disclosed in Japanese Laid-Open Patent Publication No. 2003-267201. In the system of this publication, if the host vehicle is determined to be converging on a preceding obstacle, then the system executes a control to decelerate the vehicle so as to alleviate the convergence and a control to increase an actuation reaction force exerted by the accelerator pedal. One known method of controlling the actuation reaction force exerted by the accelerator pedal is to use a reaction force control system that employs a servomotor (e.g., Japanese Laid-Open Patent Publication No. 2004-017935). In this type of system 2, the reaction force exerted by the accelerator pedal is controlled by varying a current delivered to the reaction force control system. The system is configured such that when the reaction force control system has failed, a signal line of the servomotor is grounded by using a switch lever. As a result, an induced electromotive force causes the accelerator pedal to exert a reaction force.